Journal of Agriculture and Food Research (Jun 2022)
Exploring effects of slice thickness, pretreatment and drying air temperature on nutritional, functional and pasting properties of Gardenia erubescens Stapf. & Hutch. fruit powder
Abstract
Gardenia erubescens fruits are outstanding sources of essential nutrients as well as health-promoting phytochemicals and minerals. However, fresh fruits are highly perishable and difficult to store. To reduce losses and extend their uses, fresh G. erubescens fruits could be converted into powder. The present study investigated the effect of slice thickness, pretreatment, and drying air temperature on the nutritional, functional, and pasting properties of G. erubescens fruits. Fresh G. erubescens fruits were sliced into 3 mm and 5 mm thickness, subjected to different pretreatments (steam blanching at 100 °C for 3 min, dipping in 2% (w/v) ascorbic acid solution for 3 min and no treatment) and then dried at 40 °C, 50 °C, 60 °C and 70 °C. The treatments significantly (p < 0.05) affected almost all the quality properties with trends only observed in terms of main effects. The 5 mm thick samples had relatively higher fibre, carbohydrate, zinc, iron, magnesium, manganese, swelling capacity (SC), swelling index (SI), water absorption capacity (WAC), and final viscosity (FV) but lower protein, fat, dietary energy, calcium, potassium, and sodium contents as compared to the 3 mm samples. Futher, the pretreated samples had lower protein, fat and dietary energy contents as compared to the control. Generally, potassium, calcium, zinc, iron, SI, and FV of the fruits improved by blanching but reduced by dipping in ascorbic acid solution. The SC, SI, and FV generally corresponded linearly with drying temperature with the peaks at 60 °C while WAC decreased as drying temperature increased. Blanching and dipping in ascorbic acid solution reduced SC and WAC. Though there was no three-factor combination that was ultimately the best, drying 5 mm thick G. erubescens fruit slices at 60 °C without pretreatment preserves most of the proximate and mineral contents, functional and pasting properties.
